Beamforming is a common communication technique used in wireless communication systems, in which an array of antennas is used to form respective beams to transmit or receive signals in such a manner that in directions of target devices, the antenna array creates constructive combining as the array directs towards other devices, and forms destructive cancellation. The beamforming device, such as a base station, mobile station, remote radio head (RRH) or any other transmitting and receiving device, can control the relative phase and amplitude of the signal from each transmitting/receiving antenna element to create a radiation pattern with the energy focused in a particular beam at a chosen direction to the targeted receiving device, rather than transmitting signals in all directions by using beamforming technique.
While a beamforming device using beamforming techniques performs signal transmission and reception in a multiuser communication system, radiation patterns typically include a mainlobe and one or more sidelobes. While the mainlobe is pointing toward the target device, the sidelobes are in general transmitted in all directions, causing interference with other active devices and lowering the overall efficiency in the communication system.